Stable control system and control method for descending speed of forklift portal frame

Abstract

The invention discloses a stable control system for the descending speed of a forklift gantry. The stable control system comprises a vehicle controller, a gantry sensor unit and a gantry lifting execution unit, wherein the gantry sensor unit and the gantry lifting execution unit are in communication with the vehicle controller; the portal frame sensor unit comprises a weighing pressure sensor used for detecting the weight of goods and a length angle sensor used for detecting the lifting height and the inclination angle of a portal frame. The gantry lifting execution unit comprises a pump motor controller, a pump motor and a gantry lifting proportional electromagnetic valve, the weighing pressure sensor is arranged to directly detect the weight of goods, and the weight is used as a core feedforward parameter for controlling the current of the gantry lifting proportional electromagnetic valve; the fundamental problem that in traditional control, the differential pressure of a hydraulic valve port is different due to load change, and then the descending speed fluctuates is solved, self-adaptive compensation for cargo weight change is achieved, and it is ensured that the whole-course descending speed is stable.

Description

Technical Field

[0001] This invention relates to forklift mast descent speed stabilization control technology, specifically a forklift mast descent speed stabilization control system and control method. Background Technology

[0002] The forklift mast lowering mechanism transmits an electrical signal to the vehicle controller via an operating handle. The vehicle controller outputs current to control the opening of the proportional solenoid valve, which in turn controls the oil output of the mast lifting cylinder to control the mast lowering speed. However, during testing, it was found that when the weight of the goods varies, even if the current of the proportional solenoid valve is the same, the pressure difference across the valve core due to the different weight of the goods will also be different. As a result, the mast lowering speed will vary with the weight of the goods, making it difficult to stably control the mast lowering speed. If the mast lowering speed is too slow, it will affect the work efficiency, while if the mast lowering speed is too fast, it may damage the goods or equipment. Summary of the Invention

[0003] The purpose of this invention is to provide a stable control system and method for the descent speed of a forklift mast, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A forklift mast descent speed stabilization control system includes a vehicle controller and a mast sensor unit and a mast lifting execution unit that are communicatively connected to the vehicle controller. The gantry sensor unit includes a weighing pressure sensor for detecting the weight of goods and a length angle sensor for detecting the lifting height and tilt angle of the gantry. The gantry lifting actuator includes a pump motor controller, a pump motor, and a gantry lifting proportional solenoid valve.

[0006] As a further aspect of the present invention: the input terminal of the vehicle controller is connected to an operating handle, the vehicle controller is connected to the pump motor controller via a CAN bus, the operating handle, the weighing pressure sensor, the length angle sensor are connected to the input terminal of the vehicle controller, and the output terminal of the vehicle controller is connected to the gantry lifting proportional solenoid valve.

[0007] As a further aspect of the present invention: the weighing pressure sensor is installed at the bottom of the gantry lifting cylinder.

[0008] As a further embodiment of the present invention: one end of the length angle sensor is mounted on a fixed gantry, and the other end is fixed on a moving gantry.

[0009] As a further aspect of the present invention: the output terminal of the vehicle controller is connected to a mast tilt proportional solenoid valve.

[0010] A method for stabilizing the descent speed of a forklift mast includes the following steps: Step 1: The vehicle controller receives the gantry lifting signal and controls the gantry to lift. Step 2: Obtain the weight of the cargo through the weighing pressure sensor, and calculate the target speed of the pump motor and / or the target current of the gantry lifting proportional solenoid valve based on the weight of the cargo and the set lifting speed threshold, and perform lifting control based on the target speed and / or target current. Step 3: After the gantry stops lifting, control the gantry to remain stationary for a preset stationary time T, and after the stationary time T ends, obtain the weight value of the cargo detected by the weighing pressure sensor as the reference weight value. Step 4: The vehicle controller obtains the gantry descent signal and outputs the corresponding control current to the gantry lifting proportional solenoid valve according to the reference weight value to control the gantry to start descending. Step 5: During the gantry descent, the vehicle controller receives the gantry lifting height signal detected by the length angle sensor in real time, calculates the real-time descent speed of the gantry, compares the real-time descent speed with the preset descent speed threshold, and dynamically adjusts the control current output to the gantry lifting proportional solenoid valve through PID calculation to keep the gantry descending at a stable speed.

[0011] As a further aspect of the present invention: in step 1, the vehicle controller obtains the gantry lifting signal through the operating handle; in step 2, the vehicle controller obtains the gantry lowering signal through the operating handle; in step 4, the weight value of the cargo detected by the weighing pressure sensor during the smooth lifting of the gantry is corrected by multiplying it by a correction coefficient less than 0, so as to obtain a reference weight value for controlling the pump motor speed.

[0012] As a further aspect of the present invention: the settling time T in step 3 is an adjustable parameter, and its value range is set to the time period during which the pressure at the bottom of the gantry lifting cylinder can be restored to a stable state, with T being 500ms.

[0013] As a further aspect of the present invention: In step 4, the vehicle controller pre-stores a mapping table corresponding to different cargo weight values ​​and the control current value of the gantry lifting ratio solenoid valve; the vehicle controller queries the mapping table according to the reference weight value, obtains and outputs the corresponding control current value, and the mapping table is obtained by testing and calibrating under standard loads of different weights with the goal of maintaining a stable descent speed of the gantry.

[0014] As a further aspect of the present invention: in step 5, the vehicle controller compares the real-time descent speed with the preset descent speed threshold, and dynamically adjusts the control current of the gantry lifting proportional solenoid valve through PID calculation based on the comparison result: when the real-time descent speed is greater than the descent threshold, the control current is reduced; when the real-time descent speed is less than the descent threshold, the control current is increased. When the vehicle controller 1 determines that the mast lifting or tilting motion is approaching its physical end based on the signal from the length and angle sensor, it automatically reduces the control current output to the mast lifting proportional solenoid valve and / or the mast tilting proportional solenoid valve to achieve end-point buffering; wherein, the end-point buffering of the mast tilting motion is triggered based on the tilt angle signal detected by the length and angle sensor.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This application solves the fundamental problem in traditional control where load changes cause different pressure differences at the hydraulic valve ports, leading to fluctuations in descent speed. It solves the problem by setting up a weighing pressure sensor to directly detect the weight of the cargo and using it as the core feedforward parameter for controlling the current of the proportional solenoid valve for gantry lifting. This achieves adaptive compensation for changes in cargo weight and ensures stable descent speed throughout the entire process.

[0016] 2. Based on weight-based feedforward control, this application introduces a length and angle sensor to calculate the gantry descent speed in real time, and uses PID calculation to form a speed closed-loop feedback control. This enables the system to not only respond quickly to weight changes, but also overcome interference from uncertain factors such as oil temperature fluctuations and internal system leakage in real time. The closed-loop adjustment of speed throughout the process makes the gantry descent process smooth and stable, greatly reducing the operator's workload and improving the accuracy and comfort of stacking operations.

[0017] 3. The applied length and angle sensor has the function of detecting both height and angle, which enables the system to achieve stable speed control while intelligently identifying the approach of the gantry lifting and tilting movements to the physical end and automatically triggering end-of-line buffer control, effectively reducing the impact upon arrival and ensuring the safety of goods and equipment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the control system principle in this embodiment; In the diagram: 1-Vehicle controller, 2-Pump motor controller, 3-Operating handle, 4-Weighing pressure sensor, 5-Pump motor, 6-Main frame lifting proportional solenoid valve, 7-Length angle sensor, 8-Main frame tilt proportional solenoid valve. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 In this embodiment of the invention, a forklift mast descent speed stabilization control system includes a vehicle controller 1 for controlling the vehicle. The vehicle controller 1 is connected to a pump motor controller 2 via a CAN bus. The inputs of the vehicle controller 1 are connected to an operating handle 3, a weighing pressure sensor 4, and a length angle sensor 7. The pump motor controller 2 is connected to the vehicle controller 1 via a CAN bus and is used to receive the pump motor speed control signal sent by the vehicle controller 1. The output of pump motor controller 2 is connected to pump motor 5 and is used to control the speed of pump motor; The output of vehicle controller 1 is connected to gantry lifting proportional solenoid valve 6 to control the coil current of gantry lifting proportional solenoid valve 6, thereby controlling the valve core opening of gantry lifting proportional solenoid valve 6. The operating handle 3 is connected to the input terminal of the vehicle controller 1 and is used to transmit the driver's intention to control the lifting and lowering of the mast to the vehicle controller 1. The vehicle controller 1 outputs the driver's intention to the mast lifting proportional solenoid valve 6, the mast tilting proportional solenoid valve 8 and the pump motor controller 2, thereby controlling the proportional solenoid valve and the pump motor 5 to move, so that the mast can be raised or lowered, tilted forward or tilted backward. The weighing pressure sensor 4 is installed at the bottom of the gantry lifting cylinder. The weighing pressure sensor 4 is connected to the input terminal of the vehicle controller 1. It is used to convert the weight of the goods into an electrical signal and transmit it to the vehicle controller 1. The vehicle controller 1 converts the electrical signal into a weight value as a condition for the current output of the gantry lifting proportional solenoid valve 6, thereby controlling the current value of the gantry lifting proportional solenoid valve 6. One end of the length angle sensor 7 is mounted on the fixed gantry, and the other end is fixed on the moving gantry. The length angle sensor 7 is connected to the input terminal of the vehicle controller 1 and is used to convert the lifting height and tilt angle of the gantry into electrical signals and transmit them to the vehicle controller 1. The vehicle controller 1 converts the electrical signals into speed values ​​through calculation as a condition for the output of the proportional solenoid valve current, thereby controlling the magnitude of the proportional solenoid valve current value to make the gantry lift and lower stably. It can also perform end buffer control by detecting the tilt angle of the gantry.

[0021] A method for stabilizing the descent speed of a forklift mast includes the following steps: Step 1: The vehicle controller 1 obtains the gantry lifting signal through the operating handle 3 and controls the gantry to lift. Step 2: Obtain the weight of the cargo through the weighing pressure sensor 4, and calculate the target speed of the pump motor 5 and / or the target current of the gantry lifting proportional solenoid valve 6 based on the cargo weight and the set lifting speed threshold, and perform lifting control based on the target speed and / or target current; In this embodiment, the cargo weight value detected by the weighing pressure sensor 4 during the smooth lifting of the gantry is corrected by multiplying it by a correction factor less than 1 to obtain the reference weight value for controlling the speed of the pump motor 5. Step 3: After the gantry stops lifting, control the gantry to remain stationary for a preset stationary time T. After the stationary time T ends, obtain the weight value of the cargo detected by the weighing pressure sensor 4 as the reference weight value. In this embodiment, the stationary time T is an adjustable parameter, and its value range is set to the time period that allows the pressure at the bottom of the gantry lifting cylinder to recover and stabilize. The value of T is 500ms. Step 4: The vehicle controller 1 obtains the gantry descent signal through the operating handle 3, and outputs the corresponding control current to the gantry lifting proportional solenoid valve 6 according to the reference weight value to control the gantry to start descending. In this embodiment, the vehicle controller 1 has a pre-stored mapping table of the correspondence between different cargo weight values ​​and the control current values ​​of the gantry lifting proportional solenoid valve 6. The vehicle controller 1 queries the mapping table according to the reference weight value, obtains and outputs the corresponding control current value. The mapping table is obtained by testing and calibrating under standard loads of different weights with the goal of maintaining a stable descent speed of the gantry. Step 5: During the descent of the gantry, the vehicle controller 1 receives the gantry lifting height signal detected by the length angle sensor 7 in real time, calculates the real-time descent speed of the gantry, compares the real-time descent speed with the preset descent speed threshold, and dynamically adjusts the control current output to the gantry lifting proportional solenoid valve 6 through PID calculation to keep the gantry descending at a stable speed. In step 5, the vehicle controller 1 compares the real-time descent speed with a preset descent speed threshold, and dynamically adjusts the control current of the gantry lifting proportional solenoid valve 6 based on the comparison result through PID calculation: when the real-time descent speed is greater than the descent threshold, the control current is reduced; when the real-time descent speed is less than the descent threshold, the control current is increased. When the vehicle controller 1 determines that the mast lifting or tilting motion is approaching its physical end based on the signal from the length angle sensor 7, it automatically reduces the control current output to the mast lifting proportional solenoid valve 6 and / or the mast tilting proportional solenoid valve 8 to achieve end-point buffering; wherein, the end-point buffering of the mast tilting motion is triggered based on the tilt angle signal detected by the length angle sensor 7.

[0022] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0023] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A forklift mast descent speed stabilization control system, characterized in that, It includes a vehicle controller (1) and a gantry sensor unit and a gantry lifting actuator that are in communication with the vehicle controller (1); The gantry sensor unit includes a weighing pressure sensor (4) for detecting the weight of the cargo and a length angle sensor (7) for detecting the lifting height and tilt angle of the gantry. The gantry lifting actuator includes a pump motor controller (2), a pump motor (5), and a gantry lifting proportional solenoid valve (6).

2. The forklift mast descent speed stabilization control system according to claim 1, characterized in that, The input end of the vehicle controller (1) is connected to the operating handle (3). The vehicle controller (1) is connected to the pump motor controller (2) via the CAN bus. The operating handle (3), the weighing pressure sensor (4), and the length angle sensor (7) are connected to the input end of the vehicle controller (1). The output end of the vehicle controller (1) is connected to the gantry lifting proportional solenoid valve (6).

3. The forklift mast descent speed stabilization control system according to claim 1, characterized in that, The weighing pressure sensor (4) is installed at the bottom of the gantry lifting cylinder.

4. The forklift mast descent speed stabilization control system according to claim 1, characterized in that, One end of the length angle sensor (7) is mounted on the fixed gantry, and the other end is fixed on the moving gantry.

5. The forklift mast descent speed stabilization control system according to claim 1, characterized in that, The output terminal of the vehicle controller (1) is connected to a gantry tilt proportional solenoid valve (8).

6. A method for stabilizing the descent speed of a forklift mast, applied to a stabilizing control system for the descent speed of a forklift mast according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: The vehicle controller (1) acquires the gantry lifting signal and controls the gantry to lift; Step 2: Obtain the weight of the cargo through the weighing pressure sensor (4), and calculate the target speed of the pump motor (5) and / or the target current of the gantry lifting proportional solenoid valve (6) based on the weight of the cargo and the set lifting speed threshold, and perform lifting control based on the target speed and / or target current; Step 3: After the gantry stops lifting, control the gantry to remain stationary for a preset stationary time T, and after the stationary time T ends, obtain the weight value of the cargo detected by the weighing pressure sensor (4) as the reference weight value. Step 4: The vehicle controller (1) obtains the gantry descent signal and outputs the corresponding control current to the gantry lifting proportional solenoid valve (6) according to the reference weight value to control the gantry to start descending. Step 5: During the descent of the gantry, the vehicle controller (1) receives the gantry lifting height signal detected by the length angle sensor (7) in real time, calculates the real-time descent speed of the gantry, compares the real-time descent speed with the preset descent speed threshold, and dynamically adjusts the control current output to the gantry lifting proportional solenoid valve (6) through PID calculation so that the gantry maintains a stable descent speed.

7. The method for stabilizing the descent speed of a forklift mast according to claim 6, characterized in that, In step 1, the vehicle controller (1) obtains the gantry lifting signal through the operating handle (3). In step 4, the vehicle controller (1) obtains the gantry lowering signal through the operating handle (3). In step 2, the weight value of the cargo detected by the weighing pressure sensor (4) during the smooth lifting of the gantry is corrected by multiplying it by a correction coefficient less than (1) to obtain the reference weight value for controlling the speed of the pump motor (5).

8. The method for stabilizing the descent speed of a forklift mast according to claim 6, characterized in that, The settling time T in step 3 is an adjustable parameter, and its value range is set to the time period during which the pressure at the bottom of the gantry lifting cylinder can be restored to a stable state. The value of T is 500ms.

9. The method for stabilizing the descent speed of a forklift mast according to claim 6, characterized in that, In step 4, the vehicle controller 1 has a pre-stored mapping table of the correspondence between different cargo weight values ​​and the control current value of the gantry lifting proportional solenoid valve (6); the vehicle controller (1) queries the mapping table according to the reference weight value, obtains and outputs the corresponding control current value, and the mapping table is obtained by testing and calibrating under standard loads of different weights with the goal of maintaining a stable descent speed of the gantry.

10. A method for stabilizing the descent speed of a forklift mast according to claim 6, characterized in that, In step 5, the vehicle controller (1) compares the real-time descent speed with the preset descent speed threshold, and dynamically adjusts the control current of the gantry lifting proportional solenoid valve (6) based on the comparison result through PID calculation: when the real-time descent speed is greater than the descent threshold, the control current is reduced; when the real-time descent speed is less than the descent threshold, the control current is increased. When the vehicle controller (1) determines that the gantry lifting or tilting motion is close to the physical end based on the signal from the length angle sensor (7), it automatically reduces the control current output to the gantry lifting proportional solenoid valve (6) and / or the gantry tilting proportional solenoid valve (8) to achieve end buffering; wherein, the end buffering of the gantry tilting motion is triggered based on the tilting angle signal detected by the length angle sensor (7).

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